Avaliação da contaminação microbiológica do sistema de drenagem na região da bacia do rio Infulene

Abstract

Population growth and disorderly urban development in the basins watersheds have been causing serious problems in the urban drainage of several cities, with the degradation of the quality of water resources being one of the main impacts generated by the constant urbanization of cities. The semi-urban area of Maputo city is characterized by informal settlements with systems of precarious sanitation. And the main rainwater drainage infrastructure is ditch A located on Avenida Joaquim Chissano, which receives affluents from several neighborhoods around along the drainage system. At the end of this ditch, the water is used for irrigation of crops in the so-called green zones of the city of Maputo. while the contamination microbiological contamination is imminent, the level of microbiological contamination in the drainage ditches and the relative contribution of each neighborhood. Due to these facts, it if relevant, evaluate the microbiological contamination on the drainage system. This study aims to evaluate the level of microbiological contamination of the drainage system in the Infulene river basin region. The work included the determination of field parameters (temperature, pH, total dissolved solids, electrical conductivity) and laboratory analysis (total coliforms, E.coli, nitrates, phosphates, COD and BOD). Field research was carried out during the dry season, from May to July 2022. The values ​​obtained along the main channel of Avenida Joaquim Chissano ranges between (2.46x10 4 – 1.299x10 9 MPN) and (3.1x10 3 – 9.87x10 6 MPN) for total coliforms (CT) and E – scherichiacoli (E.coli) respectively, and for phosphates and nitrates the values ​​vary between (0.23 – 32.6 mg/L) and (2.2 – 20.3 mg/L) respectively. A from the obtained results it was possible to identify the neighborhoods with influence in the contamination by domestic sewage, with the neighborhoods Chamanculo, Xipamanine, Minkadjuine, Mafalala and Aeroporto the neighborhoods that most contribute to contamination microbiology in the drainage ditch. Furthermore, the study shows that the system does not works only for the drainage of rainwater, which in addition to compromising the receiving body (Infulene River), puts the population at epidemiological risk.